World number one Aryna Sabalenka celebrated her 500th career win as she opened her WTA Tour Finals campaign in style.
The Belarussian, who won the US Open in September, is guaranteed to be at the top of the rankings at the end of the year and flexed her muscles in Riyadh.
She beat Italian Jasmine Paolini 6-3 6-1 in their opening group match at the King Saud University Indoor Arena.
Sabalenka, who is aiming for her first WTA Tour title, said on the Tour's website: "We’ve played a lot and every time it’s a tough battle.
"It doesn’t matter what the score is. I know I always have to stay focused and if you give her an opportunity she’s going to step in and take control of the game. So, I think I’m most happy with my focus today.
"I was calm and it felt like everything was under control."
In the group’s other match, American Jessica Pegula beat compatriot Coco Gauff, winning 6-3 7-6 (4) 6-2.
